Description of the Prior Art
The present invention relates to an inflatable bag. In known inflatable bags, a gas is generated through a reaction between sodium bicarbonate and an acidic solution, so as to automatically inflate the bag. Such inflatable bags are shown, for example, in Japanese Utility Model Application Nos. 77135/1985, 59188/1982, 61275/1981, 19184/1982 and 27321/1965.
In these known inflatable bags, the sodium bicarbonate charged in a sealed bag is scattered within the bag during, for example, transportation, so that the acidic solution released from a small container in the bag can hardly react with all parts of the sodium bicarbonate in the bag. In fact, the reaction between the acidic solution and the scattered sodium bicarbonate could not be attained unless the bag is shaken so as to bring the scattered sodium bicarbonate into reaction. This is difficult particularly when the bag has a large size and/or a complicated construction.
In addition, the known inflatable bag suffers from a disadvantage that the generated gas permeates through the wall of the bag in a short period of time, so that the bag deflates in a short time. When the gas is carbon dioxide gas which is soluble to water, the gas pressure is reduced very soon due to dissolution in the aqueous solution, so that the bag deflates in a very short time.
When the inflated bag is intended for use as an amusing instrument such as a ball, one can enjoy the play with this ball only for a while, due to rapid deflation of the ball. The same applies also to the case where the bag in the inflated state has the shape of a doll or an animal. Namely, in such a case, the bag can maintain the form of the doll or the animal only for a short time. For the same reason, a pillow or a cushion made of such an inflatable seat can withstand the use only for a short time.
Thus, the known inflatable bags of the kind are inconvenient and uneconomical.